A dual interface (DI or DIF) smartcard (or smart card; SC) may generally comprise:                an antenna module (AM), or transponder chip module (TCM), or RFID module,        a card body (CB) having layers of plastic or metal, or combinations thereof, and        a booster antenna (BA).        
The antenna module “AM” may generally comprise a “DI” RFID chip (bare, unpackaged silicon die) or chip module (a die with leadframe, interposer, carrier or the like)—either of which may be referred to as “CM”—mounted to a module tape “MT”. The RFID chip (CM) may be mounted on a module tape (MT), typically having 6 or 8 contact pads (CP) for interfacing with a contact reader in a contact mode (ISO 7816).
A module antenna “MA” may be disposed on the module tape MT for implementing a contactless interface, such as ISO 14443 and NFC/ISO 15693. Contact pads “CP” may be disposed on the module tape MT for implementing a contact interface, such as ISO 7816. The contact pads (CP) may or may not be perforated. The module tape MT may comprise a pattern of interconnects (conductive traces and pads) to which the RFID chip CM and contact pads CP may be connected.
The module antenna MA may be connected, indirectly, via some of the interconnects to the chip CM, or may be directly connected to bond pads BP on the RFID chip CM. The module antenna MA may comprise several turns of wire, such as 112 micron diameter insulated wire. Reference may be made to U.S. Pat. No. 6,378,774 (2002, Toppan), for example FIGS. 12A, B thereof. Alternatively, the module antenna (MA) may comprise a chemically-etched, planar module antenna MA with planar tracks surrounding the chip (CM). Reference may be made to U.S. Pat. No. 8,100,337 (2012, SPS), for example FIG. 3 thereof.
The antenna module “AM” may comprise a module antenna (MA) which has been formed from a wire wound coil which is arranged on or mounted to the module tape (MT), or may comprise a planar antenna structure (AS) which is etched (chemically etched or laser etched, from a foil on the module tape MT) to have a number of tracks separated by spaces. Generally, with laser etching, the spacing between tracks can be made smaller (such as 25 μm) than with chemical etching (such as 100 μm).
A module antenna (MA) connected to an RFID chip (CM) may be referred to as a “transponder”. Generally, such a transponder is a “passive” transponder which does not have its own power source (e.g., battery), but rather which harvests power from an external reader (interrogator).
The activation distance of an antenna module (AM) having a chemically-etched module antenna (MA), without a booster antenna (BA) in the card body (CB), may be only a few millimeters. The activation distance of an antenna module (AM) having a laser-etched antenna structure (LES), without a booster antenna (BA) in the card body (CB) may be 15-20 mm. The activation distance of antenna module (AM) with a booster antenna (BA) in the card body (CB) is typically four centimeters to meet ISO and EMV standards.
Activation and read/write distances of at least a few centimeters (cm) are desirable. However, conventional antenna modules (AM) may require a booster antenna (BA) in a card body (CB) to achieve these distances. As disclosed herein, antenna modules (AM) incorporating a laser-etched antenna structure (LES) may be able to operate without a booster antenna (BA) in the card body (CB), and may be referred to as transponder chip modules (TCM). The transponder chip module (TCM) may be referred to as a transponder IC module.
The antenna module AM (or transponder chip module TCM) may be generally rectangular, having four sides, and measuring approximately 8 mm×11 mm for a 6 contact module and 11 mm×13 mm for an 8 contact module. Alternatively, the transponder chip module (TCM) may be round, elliptical, or other non-rectangular shape. When operating in a contactless mode, the transponder chip module (TCM) may be powered by RF from an external RFID reader, and may also communicate by RF with the external RFID reader. An “activation distance” may refer to a distance at which the transponder chip module TCM may harvest sufficient energy from the RFID reader to commence operation. Similarly, a “read/write distance” may refer to a distance at which the transponder chip module TCM may communicate reliably with the external RFID reader.
The card body CB—which may be referred to as a substrate, or an inlay substrate—may generally comprise one or more layers of material such as Polyvinyl Chloride (PVC), Polycarbonate (PC), PET-G (Polyethylene Terephtalate Glycol-modified), Copolyester (Tritan), Teslin™, synthetic paper, paper and the like.
The card body CB may be generally rectangular, measuring approximately 54 mm×86 mm (refer to ISO/IEC 7810), having a thickness of approximately 300 μm thick when referred to as an inlay substrate or 760 μm when referred to as a smartcard. The card body CB is typically significantly (such as 30 times) larger than the antenna module AM.
The booster antenna BA may generally comprise a relatively large winding which may be referred to as a card antenna CA component (or portion) having a number of turns disposed in a peripheral area of the card body CB, and a relatively small coupler coil (or coupler antenna) CC component (or portion) having a number of turns disposed at a coupling area of the card body CB corresponding to the location of the antenna module AM.
The card antenna CA and coupler coil CC may comprise wire mounted to (embedded in) the card body CB using an ultrasonic tool comprising a sonotrode and a capillary. See, for example U.S. Pat. No. 6,698,089 and U.S. Pat. No. 6,233,818. The wire may be non-insulated, insulated, or self-bonding wire, having an exemplary diameter in the range of approximately 50-112 μm.
Some examples of smartcards (SC) with booster antennas (BA) may be found in . . .                U.S. Pat. No. 8,474,726 issued 2 Jul. 2013        U.S. Pat. No. 8,366,009 issued 5 Feb. 2013        U.S. Ser. No. 14/020,884 filed 8 Sep. 2013 (now US 20140091149 3 Apr. 2014)        
Metallized smartcards may have a faceplate or layer of metal extending over nearly the entire area of the card (except for an opening for the antenna module (AM)), and some smartcards may be made largely of metal. The presence of such a metal layer or mass in the smartcard may tend to attenuate contactless communication (e.g., ISO 14443, ISO 15693) between the smartcard and an external reader. The contact pads themselves may also tend to attenuate contactless communication. Hence, metallized smartcards may often function in a contact mode (e.g., ISO 7816) only.
Foil composite cards and metal cards may be disclosed in . . .                US 20090169776 (2009 Jul. 2; Herslow)        US 20110189620 (2011 Aug. 4; Herslow)        
Shielding layers and the like may be disclosed in . . .                U.S. Pat. No. 8,261,997 (2012 Sep. 11; Gebhart/NXP)        EP1854222 (NXP)        EP 02063489 (Tyco)        
U.S. Ser. No. 13/744,686 filed 18 Jan. 2013 (now US 20130126622, 23 May 2013) discloses offsetting shielding and enhancing coupling in metallized smart cards. As disclosed therein (FIG. 4A), a conductive “compensation loop” CL may be disposed behind the booster antenna BA, extending around the periphery of the card body CB. The compensation loop CL may be an open loop having two free ends, and a gap (“gap”) therebetween. The compensation loop CL may be made of copper cladding.
Some other patents of interest may include . . .    U.S. Pat. No. 8,393,547 issued 2013 Mar. 12 (Kiekhaefer et al.; Perfect Plastic)    US 20140166762 published 2014 Jun. 19 (Herslow)
Some terms used herein may include:                “skin depth” relates to the “skin effect” which is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor. A “skin depth”, or minimum thickness for conducting current may be defined, for a given material at a given frequency. For example, at 13.56 MHz, the skin depth for copper may be approximately 18 μm (17.7047 μm).        “transparency” refers to the ability of electromagnetic radiation to pass through a material. A threshold for non-transparency (or the ability to interact with RF) may be a fraction of the skin depth for the metal layer in question at a given frequency of interest. For example, the non-transparency threshold for copper at 13.56 MHz, may be one-tenth of the skin depth, or approximately 1.7 μm.        